Functionalization Enhanced Phase Separation in PS-b-PVP Derived Polyzwitterionic Block Copolymers

Block copolymers with strong tendency for block demixing have attracted significant attention especially for applications in microelectronics and membranes. Enabling technological advances in these areas critically depends on access to well-defined nanostructures with dimensions near or below 10 nm. Block copolymers bearing polyzwitterionic segments are a promising class of materials for phase separation due to their ion association-induced phase segregation which bestow high-χ. In this work, the synthesis of parent poly(styrene)-block-poly(vinylpyridine) (PS-b-PVP) block copolymers that are subsequently modified to the targeted poly(styrene)-block-poly(vinylpyridine carboxybetaine) using a two-step modification scheme is presented. We study the thermophysical and phase separation properties of the parent, polyelectrolyte intermediate and the final polyzwitterionic block copolymers. Ultra-small, periodic nanostructures with half-spacing as low as 5.3 nm are obtained from the polyzwitterionic copolymers. This work demonstrates a scalable synthetic methodology to access pH responsive polyzwitterions and establishes connectivity between polymer design attributes and phase separation behavior for neutral-block-polyzwitterionic copolymers.